The history of African Americans in the American Civil War is marked by 186,097 (7,122 officers, 178,975 enlisted) African Americans comprising 163 units who served in the Union Army during the Civil War, and many more African Americans who served in the Union Navy. Both free African Americans and runaway slaves joined the fight. On the Confederate side, both free and slave blacks were used for labor, but the issue of whether to arm them, and under what terms, became a major source of debate, and no significant numbers were ever raised or recruited.